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What is a peak load and how does it affect you?

Over the past few weeks of intense heat waves, utilities across the United States have been facing elevated peak loads due to increased demand for power. During periods of extreme weather, utilities experience elevated load demands which result in higher-than-normal peak loads. Extreme heat has been less of an issue historically in the Seattle region thanks to our mild temperate climate. However, in recent years, climate change has fueled extreme heat and cold weather events which has led to increased demand for electricity.

What is a peak load?

Peak load is when a utility reaches the highest level of energy that customers draw from an electrical system at any given period such as an hour, day, month or year. During peak load hours, utilities are expected to provide power at a significantly higher rate than normal levels. City Light’s priority is to provide our customers with affordable, reliable and environmentally responsible energy services when they need them, and we strategically manage our power supply to meet peak loads.

Summer peak loads are often seen during the evening between 4 and 10 p.m. This is often during and immediately after the hottest parts of the day. It’s also when most of us are getting home from school or work, turning on lights and electronics, and cooking dinner. During the hottest days of the year, we also tend to crank up our AC and fans to keep cool, creating high demand on the electrical system.

How does it affect you?

While City Light is traditionally a winter peaking utility, hotter summers and the increased use of air conditioning and heat pumps are driving summer energy demand upward. During the 2021 Heat Dome event, we saw a record summer peak of 1533 MW, which is roughly 500 MW more than we typically see during the summer months.

Increased load during heat events has the potential to cause unplanned outages and impacts on our ability to meet demand for all customers. It also can be quite expensive if we need to acquire additional resources to meet peak load. Increased demand around the region can lead to much higher-than-normal prices on the wholesale energy market. City Light can typically make operational adjustments to help meet increased load activity. However, there may be instances in the future where we may need to ask customers to conserve energy to help ensure there is enough power for everyone and to keep costs low.

What can you do to help?

Saving energy is always a good idea for your wallet and the planet. When everyone does their part to conserve energy, we all win. Reducing individual use adds up to a lot when we all work together as a community.

Here are some quick tips you can follow to help ensure there is enough energy for everyone to stay safe and cool during periods of extreme heat:

Trap cold air in the morning
Before the day starts to heat up, close your windows and draw the blinds on windows that are exposed to the sun. Try to keep windows or doors shut when it’s cooler inside than outside.

Precool your home when possible

If you have AC in your home, run it in the morning to bring down the overall temperature in your home early. You’ll use less energy maintaining a cool home than a hot one.

Avoid heating your home with appliances  
Large appliances like ovens and ranges can heat up more than just your food; they can also heat up your home! Try recipes that require minimal cooking or use appliances like microwaves, electric pressure cookers or even cook outside on a grill. 

Install window treatments 
Energy-efficient windows or coverings such as blinds, shades and films greatly reduce heat in your home when temperatures rise.  

Replace air filters 
If your home’s heating/cooling system has an air filtration system, be sure to change out your filters. Changing out your air filters not only improves the air quality in your home, it also makes your home more energy efficient.    

These are just a few of the energy saving tips that you can take to help keep cool, save money, and reduce peak loads during periods of extreme heat. For more tips, visit our recent Powerlines blog on how to stay comfortable without using electricity this summer.